1. Field of the Invention
The present invention relates to a rotational drive device that provides both variable levels of adjustable rotational resistance and also selective direction in which the resistance acts. The invention finds application in exercise equipment wherein a user overcomes the resistance when using the equipment. The device may comprise an exercise device having two handles to be grasped by the two hands of the user, who rotates the handles relative to one another, or alternatively may be incorporated into a more complicated machine.
2. Description of the Prior Art
Many different types of rotational exercise devices have been designed in the past. Most of these exercisers include means to adjust the rotational resistance in one or both directions. What is lacking in the prior art is a rotational exercise device that can be adjusted to provide selectively variable resistance in either one or both of opposed directions, and which offers selection of the direction of resistance.
Exercise devices are shown in U.S. Pat. Nos. 2,543,729 and 2,725,232, issued to Herbert N. Magida respectively on Feb. 27, 1951, and Nov. 29, 1955. In both cases, the subject devices include two handles, one for each hand of the user, and an adjustably variable frictional resistance element. Resistance is the same regardless of direction of rotation of one handle relative to the other. By contrast, the present invention enables the user to select the rotational direction in which resistance acts. Optionally, resistance acts in both directions.
U.S. Pat. No. 5,788,618, issued to Frank Edward Joutras on Aug. 4, 1998, describes an exercise device having a ratchet mechanism and an adjustable resistance feature. However, Joutras lacks a directional selector for selecting direction of resistance, as seen in the present invention.
U.S. Pat. No. 5,557,984, issued to Tatsuo Nakayama on Sep. 24, 1996, shows a ratchet wrench which includes torque adjustment and an adjustable selector for selecting the direction of resistance. A ratchet wrench is intended to rotatably drive a device such as a threaded fastener to the point of tightness, and therefore lacks a second handle as seen in the present invention, which second handle would be appropriate for exercise devices. Also, a wrench intended for rotating a fastener would not provide resistance in two opposed directions, with the consequence that no significant progress could be achieved in turning a fastener.
The prior art devices, in addition to failing to show the combination of variable resistance and selection of direction in which the resistance acts, lacks a stepless ratchet mechanism. As employed herein, stepless ratchet action signifies action from which arise neither the sound nor the tactile characteristics of a rapidly oscillating or striking sequence generated by a ratchet wherein a pawl contacts a series of steps in rapid progression. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
The present invention is a dynamic tensioner particularly suitable for use in exercising. The tensioner includes two rotatable members which rotate about a common axis. In one embodiment, the tensioner has two handles each grasped in one hand by the user, wherein one handle is attached to each rotatable member. A frictional resistance element opposes relative rotation of the two handles. The tensioner incorporates both a directional selector and a variable resistance adjuster. The device therefore provides variable resistance to rotation of the rotatable members and associated handles, which resistance may be varied both in magnitude and in direction. More specifically, the variable resistance selectively acts in either one of two opposed rotational directions, wherein almost no resistance acts in the opposite rotational direction, or alternatively, equal resistance in both rotational directions. Thus three directional options are provided by the selector, in addition to selection of level of frictional resistance provided by the resistance adjuster.
The directional selector is a three position dial which biases a plurality of cams into one of three possible positions to transmit selected frictional resistance forces only when the first member is rotated clockwise relative to the second member, only when the first member is rotated counterclockwise relative to the second, and in both rotational directions. The tension adjuster includes a threaded fastener which compresses the two rotatable members into mutual engagement. As increasing axial forces press the two members together, frictional resistance to rotation increases. The two members undergo only partial rotation relative to one another. Alternatively stated, they move only through a limited arc of motion.
This motion, combined with selected frictional resistance, allows specific muscle conditioning for any limb of the body which engages one handle of the tensioner. The two handles or their corresponding members may pit effort of one limb against effort exerted by another limb. Alternatively, one handle or corresponding member may be immobilized, with only one body limb engaging a handle or corresponding member. In the latter example of usage, a single body limb is subjected to exercise. Thus the present invention is particularly suited for physiological sculpting.
A clutch transmits compressive forces from the tension adjuster which generate resistance in selected mutual rotational directions. The clutch, unlike a stepped pawl and ratchet device, acts steplessly. That is, motion of one rotatable member relative to the other proceeds smoothly in both directions without causing rapid vibrations or chatter typical of stepped pawl and ratchet devices.
In the preferred embodiment, the frictional resistance element comprises two members having opposed, interfitting, complementary ramps. The members are formed from a mildly elastic, strong material such as a steel alloy. When ramps of each member are pressed against one another, each ramp deforms slightly to accommodate passage of its opposed counterpart.
Accordingly, it is one object of the invention to provide a dynamic tensioner which varies both magnitude and direction of resistance forces acting on two mutually rotatable members.
It is a second object of the invention to enable alternating direction of the two mutually rotatable members by stepless ratchet action.
Another object of the invention is to provide a dynamic tensioner which is engaged by, selectively, one or two limbs of a user, and which pits effort of one arm against selected resistance forces.
It is a further object of the invention that the tensioner provide selectively variable frictional resistance to rotation of one rotatable member relative to the other rotatable member.
Still another object of the invention to enable a user to select one of two opposed directions of rotation or both directions when subjecting the rotatable members to frictional resistance to rotation.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.